The Thermal Analysis and Structure Transformation of TiO₂ Ultrafine Powders

TiO₂ xerogel powders was prepared in the nonpolar solvent by sol-gel method. The thermal stability of TiO₂ xerogel powders was investegated in Air or in Ar by TG-DTA, The crystallization processes of TiO₂ xerogel powders, from amorphous to anatase, were studied in Air or in Ar by dynatic DTA, The crystallization activation energies were computed following Avrami model, E_Air= 135kJ/ mol, E_Air= 178kJ/ mol. The grain growth behaviours of nanomet-er-anatase were analysed in O₂ in the different temperature ranges by X-ray diffraction and TEM mothods, The activation energise of grain growth were calculated in terms of grain size varing with temperture, Q₁=78kJ / mol, Q₂ = 52kJ / mol.